Refrigeration



March 4, 1930. KNlGHT I 1,748,957

REFRIGERATION} I /-,-v VENTOAT D. B. KNIGHT March 4, 1930.

REFRIGERATION 2 Sheets-Sheet Filed May 24, 1928 INVENTOR Patented Mar. 4, 1930' v UNITED STATES] M11:NT OFFICE,

DONALD B. KNIGHT, OF BROOKLYN, NEW YORK v REFRIGERATION application niea May 2i,

This invention relates to the system of refrigeration described in Letters Patent of the United States No. 1,609,334, dated December7, 1926. In that system, as disclosed in said Letters Patent, the development of internal pressure is a necessary incident. This requires the apparatus to be so constructed as to be capable of resisting such pressure, with consequent expense. It .also subjects the appara'tus to restrictions imposed by local communities and to regulations of the Interstate Commerce Commission governing the use and shipment of compressed gases. It creates sales resistance due to fancied or real dangers attending the use of gases under compression. It'requires careful tests to insure. reasonable safety. It involves service cost due to leakage. It requires expenditure of time and labor in charging the apparatus and in purging it. a It is the object of the present invention to enable refrigeration by methods of the general character of that described in said Letters Patent to be carried on at atmospheric pressure, without the development of internal pressure of material degree in any part of the apparatus and without subjection to such objections as have been described above.

In "accordance with the invention the cooling agent employed is of relatively low vapor pressure and is evaporated in the presence of an inert auxiliary agent at atmosphericvpressure, the circulation of the auxiliary agent being accomplished also under substantially atmospheric pressure, by diiference in specific weights of vertically extending bodies of fluid in the system. It will be seen that the invention is characterized by, the employment of a cooling'agent ofrelatively 10w vapor ressure,

vsuch, for example, as a solution of p enol or kerosene and ether andan auxiliary agent, such, for example, as nitrogen or atmospheric air into which and in the presence of which the ether-diffuses and evaporates, all'under atmospheric pressure. a

In the practice of the invention the following conditions should be established. The refrigerating fluid 'should be condensible at atmospheric pressure at a temperature, such as normal room temperature,

with the available cooling water or other confunction. As will be seen hereinafter,

evaporator shown and described herein has easily reached.

192s. Seria QNo. 280; 9-

densing means. The auxiliary agent should be gas lighter per unit volume than the vapor of the refrigerating fluid and chemically inert to it. The absorption medium should be such that atatmospheric pressure it will absorb the vapor of the refrigerating fluid even though it is greatly diluted by the auxiliary fluid, it being apparent that if the auxiliary agent has a great effect upon the ability of the refrigerating fluid to evaporate in the evaporator, it will have the same tendency in the absorber. The auxiliary agent should be present in large volume in order that a suiii-.

ciently low evaporating temperature may be attained with a liquid of relatively high boiling point, the vapor of therefrigerating fluid being, therefore, very dilute in the auxiliary agent and requiring a powerful absorbent fluid for its removal. The process must be carried on in such manner that the refrigerat- ,ing fluid will be evaporated in suflicient quantity to realize a practical amount of refrigera tion of the relatively heavier refrigerating fluid is dependent primarily upon the evaporation of that fluid and the method of evaporation is therefore of great importance. The design of the evaporator is therefore of importance, particularly with a view to the prevention of the formation of a protective blanket of vapor which would tend to prevent the auxiliary agent from performing its been designed to meet this condition.

The invention will be more fully explained with reference to the accompanying drawings in which it is illustrated and in which:

' Figure 1 is a somewhat diagrammatic view,

the

in sectional elevation, showing a form of apparatus adapted for the practice of the invention.

' Figure 2 is a detail view showing the construction and arrangement of the refrigerating chamber as seen from above, with the top removed.

Figure 3 is a detail view in perspective illustrating particularly the connection of one of the trays of the refrigerating chamber to the ice' chamber.

Figure 4 is a detail view in perspective of one of theasbestos sheets which forms the bottom of one of the trays of therefrigerating chamber as seen from below, with its frame.

Figure 5 is a detail view illustrating the construction and arrangement of the refrigerating chamber, icechamber and trays, as seen from the left-hand in Figure 1 with the end wall'removed.

Figure 6 is a detail view illustrating the arrangement of the trays in the absorber.

Figure 7 is a fragmentary view showing the application of cooling water pipes to the trays in the absorber.

The cooling agent, which for purposes of explanation of the nature of the invention and by way of example only, may be .taken to be a solution of phenol or kerosene and ether maybe introduced into .the apparatus through a filling plug conveniently located,

as at 70, in a generator, as at K, and the auxiliary agent, which may also be taken for purposes of. explanation and by way'of example only, to be nitrogen or atmospheric air, may

be introduced into the apparatus at any' convenient point as through the vent pipe a which at its open upper end terminates above the rest of the apparatus. By a suitable source of heat, indicated alt-14, the cooling.agent is heated and is caused to rise through a pipe 11 to the upper part of a condenser or separator K which is inde endent of the generator K and in whic the vapor of the heated cooling agent is separated from the absorption liquor, such as phenol or kerosene, for example, which is in solu-' tion with the ether or its functional equivalent. From the separator K the vapor of the cooling agent passes upward through the pipe '11 which may include at E a rectifieror air condenser by which any vapor of the absorption liquid which may have been carried upward with the 'vapor of the cooling agent is condensed andseparated to hereturned to the separator K s Substantially at the highest point of the apparatus the vapor enters a condenser 0 within which is a pipe B suitably connected to a continuous supply of cooling water.

I The condensed vapor, which is rich in ether or its equivalent, is conducted from the condenser C through the-pipe 12 to the evaporator G which is placed within the refrigeratreason of its own specific gravity downward I through the pipe M and its extension M to the lower part of the absorber A, the pipe M preferably enclosing an inner pipe N, through which the relatively lighter auxiliary agent passes upward from the uper part of the absorber A to the upper part of the evaporator G, the described relation of pipes l\/I and N forming a heat exchanger by means of which the desired circulation of the vapor of the cooling agent and the auxiliary agent a between the evaporator G and the absorber A is promoted.

WVithin the absorber A the solution of the cooling agent and the absorption liquor takes place, the construction of the absorber, as will be'explained more fully hereinafter, being such that the concentration of the solution progresses. I

The absorption. liquor is delivered to the absorber A from the separator K through the pipe P connected to the separator K near its lower end, a heat exchanger vT, and

a precooler X, from which the-absorption liquor, poor in cooling agent, is delivered through'the pipe P to the upper part of the absorber A, passing by gravity to the lower part of the absorber and becoming progressively concentrated. It;will be observed not only that the absorption liquor is mostly concentrated in the lower part ofthe absorber A, but that the vapor of the cooling'agent from the'evaporator G attains its highest strength as it reaches the lower partof the absorber A,

From the absorber A the concentrated solution passes through a pipe L, the external portion of the heat exchanger-T, and the pipe extension L back to the generator K where 7 the cycle begins its repetition. The pipe L is preferably extended upward with the absorber for a short distance as represented in the drawing in order that the concentrated liquor may accumulate to a moderate depth in theabsorber, the absorption of the cool-.

ing agent, in its richest condit'on, being carried on at thesurface of the'liquor in the lower part of the absorber.

It being one purpose of the present invention to permit the refrigeration to. be carried on at substantially atmospheric pressure, connection fromtheabsorber to the atmosphere is established through the vent pipe (1, the open upper end of .Whiclnas previously protecting blanket,'. thevapor thus disens'tated, terminates above the rest of the apparatus.

To equalize the pressure in the several parts of the apparatus, to prevent the building up of pressure on the generator'side, andto permit the escape of air which may be carried over with the vapor from the generator, 2; direct vapor connection between the vapor space of the condenser C and the evaporator is established through a pipe 0.

It being very desirable that evaporation of the cooling agent shall proceed as rapidly as possible in the evaporator, the construction of the evaporator shown in Figures 2, 3,- 4 and 5 is preferred. As shown particularly in Figure. 2, the evaporator is formed with two wings or parts G and Gr which are substantially identical in construction and receive between them the ice chamber H in which ice may be formed if desired.- Each part or wing comprises a series of horizontal traysg which may be secured by solder or otherwise tothe walls of the ice chamber H. Each tray is formed with alower flange g and with a series ofrelatively large openings 9 which areclosed from the underside by a sheet 9 of asbestos or other suitable material, secured to the underside of the tray g, which may be secured to the tray in any convenient manner,- as by bolts at g. The cooling agent is delivered by a branch 12* or 12 to the uppermost tray, of each series and, through the openings 9 saturates the asbestos sheet from the'underside of which evaporationof the cooling agent proceeds rapidly, without the formation of a gaged at atmospheric pressure passing down through the pipes Nto the absorber, as already explained. The absorber is so constructed as to promote absorption by the absorption liquor of the cooling agent at the surface of the liquor. Accordingly 1t is provided interiorly with a series of horizontal a each of which is provided, as

trays a, a

an outlet which is' raised slightly at a with above the accumulation of the absorption hquor to a moderate-depth. .The outlets a are staggered so that the liquor flows over the whole surface r of the trays, exposinga large surface for absorption of the auxiliary agent .Withinthe absorber. As the absorption liquor passes from one tray to the next below itand eventually to the bottomof the'absorber vessel the liquor becomes more and more concentrated until it is in readiness to be returned to the generator. For the purpose of cooling theabsorber and the absorption liquor during the process of absorption a cooling water pipe 0, connected to a suitable supply, is introduced into the absorber at a convenient point, and is soldered to the underside of each tray a, a a,

with many turns, and is eventuallyled from by a light frame bottom of the tray so as to permit the absorber A, as at 0 passing through th pre-cooler and discharging as at 0 In operation it will be understood that when heat is applied to the generator K the solution is raised from the generator into the separator K the ether or. other cooling agent being at the same time separated from the absorption liquor, such vapor, being freed as far as possible from the trays of absorption the presence of the auxiliary agent, such as air or nitrogen or other suitable agent which is non-condensible at the temperature at which it operates and is inert with respect to the other chemical substances within the apparatus. In the presence of such auxiliary agent the ether or other cooling agent difiuses and evaporates into the-auxiliary agent,'heat being thereby abstracted from. the surround-' ings while no change in'actual or total pres sure as between the condenser and the evaporator is necessited.

It will be observed that either nitrogen or air or some functionally equivalent agent may the cooling agent. Because-such an auxiliary agent and such a cooling agent have specific and molecular weights which differ greatly with the result it is possible to obtain eflicientcirculation and eflicient diflusion,

The ether vapor and auxiliary agent mingle in the evaporator and flow downwardly into the lower part of the absorber A where the gaseous mixture comes in contact with the weak absorption liquor supplied thereto from the separator K amount of the cooling agent, such liquor being preferably ;pre-cooled before it enters the absorber. r I

Through the established r lation of the gaseous mixture and, the absorption liquor there results an absorption or dissolving of the ether by the absorption liquor and a liberation ofthe auxiliar auxiliary agent, is of marl cific wei ht than theqcooling agent and is very muc lighter than the cooling agent, it will be seen that theweight per unit volume of gas after it is freed from the ether or other cooling'agent in the absorber is less' than the weight per unit volume of the gasthat is with the liquor in which there is dissolved a relatively less agent. Since the edly diflt'erent speeous mixture in the evaporator-T As a resultthere will be a constant circulationof fluids between theabsorber'an'd the evaporator.

- Inthe operation as thus described the .head

under'which the movement takes placeis produced rather .by difference in the degree of the mixture than by absolute separation 95. be employed: advantageously with ether as I agent exerts a permit it to evaporate at freezing tempera-' of the elements and subsequent admixture. Some of the ether and other cooling agent passes upward through the pipe M from the absorber along with the auxiliary agent to the evaporator, but the amount of cooling agent thus entrained is small relatively to the proportion of the cooling agent in the mixture within the evaporator.

Absorption liquor, saturated with the coolingagent, is carried from the absorber into the generator K under the influence of the heat applied to the generator. As vapor is formed within the generator it pockets some of the absorption liquor while it is escaping through the conduit 11 and such bodies of liquor will thereby be lifted into the upper part of the separator K displaced in the generator K is replaced by additional strong liquor from the absorber, while the weaker liquor, which has beenseparated in the separator K runs by gravity back into the absorber.

It will be seen that while the actualor total pressure in the apparatus remains at substantially atmospheric pressure, there is a variation as between actual pressures in the evaporator and absorber, the sum of which is equal to the actual or total pressure.

It will further be understood that as the apparatus functions at substantially atmospheric pressure the partial or differential pressures of the cooling agent and the auxiliary agent are respectively below atmospheric pressure and that the lower the pressure of the cooling agent becomes the lower will be the temperature at which it will evaporate, the presence of the auxiliary agent not only permitting operation at constant total pressure, but if present in sufficient quantity to exert sufiicient partial pressure the cooling partial pressure low enough to tures. Thus the auxiliary agent permits operation at a uniform total pressure and operation at substantially atmospheric pressure, such atmospheric pressure being dependent to some extent upon the amount of auxiliary agent present.

i It will be observed that the operation of the system embodies the circulation of the cooling agent from the generator, through the condenser, through the evaporator, through the absorber and back to the generator; a local circulation of the auxiliary agent between the evaporator and the absorber; and a local circulation of the absorption liquor between the generator and the absorber.

- I claim as my invention:

- 1. The process of refrigerating which comprises evaporating a liquid cooling agent of relatively low vapor pressure in the presence of an auxiliary agent inert to the cooling agent at substantially atmospheric pressure, producing a head due to difference in specific weights of a mixture of the vaporof The liquor thus.

the cooling agent and the auxiliary agent on the one hand and the auxiliary agent on .the presence of the mixture, condensing the cooling agent at substantially atmospheric pressure, and returning the condensed cool ing agent into the presence of the auxiliary agent.

2. The process of refrigerating which comprises evaporating a liquid cooling agent of relatively low vapor. pressure in the presence of an auxiliary agent inert to the cooling agent and ,at substantially atmospheric pressure and having a specific weight lower than the specific weight of the vaporof the cooling agent, producing a head due to difference in specific weights, forcing the mixture of the vapor of the cooling agent and auxiliary agent under the influence of the head produced into the presence of an absorption liquor at substantially atmospheric pressure, segregating the cooling agent from the auxiliary'agent by absorption, and re turning the auxiliary agent into the presence of the cooling agent under the influence of the head produced.

3. The improvement in the procss of re frigerating by the aid of a system including an evaporator and an absorber which consists in diffusing a cooling agent of relatively low vapor pressure in the presence of an auxiliary agent in the evaporator at substantially atmospheric pressure, and circulating under substantially atmospheric pressure the auxiliary agent through the evaporator and the absorber exclusively by difference in specific weights of vertically extending bodies of fluid in the system.

This specification signed this 22nd day of May, A. D. 1928. A

DONALD B. KNIGHT. 

